Financing Sustainable Water: Effective Rate Modeling in an Uncertain World
AWE Sales Forecasting and Rate Model
Why a New Rate Model? Typical water rate models assume that future sales are known with certainty, and do not respond to price, weather, the economy, or supply shortages — that is to say, not the world we live in. The AWE Sales Forecasting and Rate Model addresses this deficiency: Customer Consumption Variability — weather, drought/shortage, or external shock Demand Response — Predicting future block sales (volume and revenue) with empirical price elasticity's Drought Pricing — Contingency planning for revenue neutrality Probability Management — Risk theoretic simulation of revenue risks Fiscal Sustainability — Sales forecasting over a 5 Year Time Horizon Affordability — Can customers afford water service?
WHERE MODEL FITS INTO RATE SETTING PROCESS Cost of Capital Cost Service/Revenue Rate Design Planning Allocation Requirements Model Does Not Do These Things Model Useful Here
Modular Design Rate Design Module Revenue Simulation Module
Model Setup
Model Setup
Rate Design Module
Questions the Rate Design Module Can Address What effect would increasing the rate in our top tier by 15% have on water demand? Will shifting to seasonal rates cause overall water use to increase or decrease? What block rate design could allow us to preserve our current level of revenue while reducing overall demand? What proportion of customer bills will increase (or decrease) under our proposed rates when compared to our current rates? How should we adjust our rates to support our water demand management objectives during water shortages?
What Rate Designs Can Be Modeled? Rate Designs Uniform Seasonal Block Seasonal Block Up to 5 blocks Can vary rates and blocks by customer class Up to six customer classes
What Data is Needed to Use It? Bill Tabulations from Billing System Data By Class By Season (Off-Peak, Peak) Follows AWWA M1 Bill Tabulation Methodology Allocating Bills to Seasons Easy when bills are rendered monthly Bit harder when bills are rendered bi-monthly or quarterly
Bill Tabulation Screenshot
Rate Design Table Block # Block Switch Point Rate for Block Block 1 10 $2.50 Block 2 20 $3.00 Rate for first Block 3 $3.75 10 units Block 4 $3.75 Rate for next Copy rate in Block 5 10 units $3.75 last block to unused blocks Rate for units in excess of 20
Rate Design Screenshot Rate Performance Indicators Rate Design Tables 2. Specify rates for each Customer Class in the tables below. Save/Load Rates button Use the tables below to specify the Current and Proposed rates for each Customer Class. You can specify uniform, block, seasonal, and seasonal block rates. Save/Load Rates Uniform and Uniform Seasonal Designs : Enter the same rate for all five blocks. If you want the uniform rate to vary by season, set a different uniform rate for each season. Block and Seasonal Block Designs : Enter the blocks and rates for each block level. You can specify up to 5 blocks. If you want fewer blocks than 5 -- say 3 -- then enter the same rate and Impact of Proposed Rates block information for Block 4 and Block 5 that you did for Block 3. If you want seasonal block rates, you can specify different blocks and/or rates for each season. Relative to Current Rates Mixed Designs : You can vary the rate design by Customer Class and season. For example, you can specify a block rate for the single family residential class and uniform rates for all Annual Annual other classes. Or you can specify a uniform rate for one season and a block rate for the other. Rate Performance by Customer Class Sales Volume Service & Volume Revenue (% Change) (% Change) Single Family Off Peak Season Peak Season Annual Sales Volume 50% 1.2 50% 1.2 Current Rates Proposed Rates Current Rates Proposed Rates Current Proposed % Change Block Rate Block Rate Block Rate Block Rate CCF 9,069,061 8,913,705 -1.7% 1 1 30% 30% (CCF) ($/CCF) (CCF) ($/CCF) (CCF) ($/CCF) (CCF) ($/CCF) 0.8 0.8 10% 10% Block 1 5 $3.00 5 $2.50 5 $3.00 5 $3.75 Annual Revenue (Thou. $) 0.6 0.6 Block 2 10 $3.00 10 $2.50 10 $3.00 10 $3.75 Current Proposed % Change -10% -10% 0.4 0.4 Block 3 15 $3.00 15 $2.50 15 $3.00 15 $3.75 Service $12,263 $12,263 0.0% -30% -30% Block 4 15 $3.00 15 $2.50 15 $3.00 15 $3.75 Volume $27,207 $27,744 2.0% 0.2 0.2 Block 5 15 $3.00 15 $2.50 15 $3.00 15 $3.75 Total $39,470 $40,007 1.4% -50% 0 -50% 0
Bill Impacts Screenshot Affordability Indicator 3. Bill impacts of Proposed rates Avg and Under your Proposed rates, the volume charge may go up for some customers and down or stay the same for others. The Bill Impacts Table shows the percentage of bills that will go down, stay the same, or go up -- and by how much. Charts showing the distribution of bill impacts for each customer class are provided on the Bill Impacts worksheet. median bill impacts Affordability Index % Change in Average and Median Annual Water Service Cost by Customer Class Current Proposed Average Annual Water Service Cost Median Annual Water Service Cost Affordability index equals 5.0% 5.0% Customer Class Current Proposed % Change Current Proposed % Change the median annual water 4.0% 4.0% Single Family $777 $804 3.4% $650 $672 3.3% cost for the primary 3.0% 3.0% Multi Family $4,254 $4,294 0.9% $1,930 $1,942 0.6% residential customer class CII $3,323 $3,382 1.8% $1,481 $1,504 1.5% divided by median 2.0% 2.0% Landscape $5,599 $6,007 7.3% $2,503 $2,720 8.7% household income. 1.0% 1.0% Not in use 0.0% 0.0% Not in use Bill Impacts Table % of bills decreasing by No More Than % of bills increasing by Customer Class more than 20% 15 to 20% 10 to 15% 5 to 10% +/- 5% 5 to 10% 10 to 15% 15 to 20% more than 20% Single Family 0% 0% 21% 38% 9% 4% 17% 11% 0% Multi Family 0% 1% 38% 25% 4% 4% 18% 12% 0% CII 0% 0% 25% 20% 28% 7% 9% 10% 0% Landscape 0% 0% 26% 12% 33% 2% 6% 20% 0% Not in use Not in use Bill Impact Single Family Customer Class Bill Impact Histogram Histograms 50% Percent of Bills 40% 30% 20% 10% 0% more than 20% 15 to 20% 10 to 15% 5 to 10% No More Than 5 to 10% 10 to 15% 15 to 20% more than 20% +/- 5% % Decrease in Bill % Increasein Bill
Drought Rates Evaluate rate performance under water use curtailment Up to 4 drought stages can be specified Curtailment levels can vary by customer class User can design rates “by hand”, OR Use built-in calculator to find revenue-neutral rates by drought stage
Specifying Curtailment Levels Requested curtailment level by stage 1. Specify Curtailment Levels for Drought/Shortage Stages 1. Enter the Customer Class curtailment levels for each stage. If you have fewer than 4 stages, enter the last curtailment level in the unused stages. Stage 0 is the default No Shortage condition. Do not modify the settings for this stage. 2. For each stage, enter the expected compliance rate. The compliance rate can vary by stage. For example, stages with voluntary curtailment may have lower compliance than stages where curtailment is mandatory and enforced. The expected curtailment level for a stage is the product of the stage's curtailment level and the expected compliance rate. Drought/Shortage Stage Customer Class Curtailment Levels Table Expected Curtailment Customer Class Stage 0 Stage 1 Stage 2 Stage 3 Stage 4 Stage 0 Stage 1 Stage 2 Stage 3 Stage 4 Single Family 0% 10% 15% 20% 25% 0% 8% 12% 17% 21% Multi Family 0% 10% 15% 20% 25% 0% 8% 12% 17% 21% CII 0% 0% 10% 20% 25% 0% 0% 8% 17% 21% Landscape 0% 0% 10% 20% 25% 0% 0% 8% 17% 21% Not in use 0% 0% 0% 0% 0% 0% Not in use 0% 0% 0% 0% 0% 0% Enter Expected Compliance % 100% 80% 80% 85% 85% Expected compliance rate Expected curtailment
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